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| author | Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> | 2019-02-19 11:04:51 -0800 |
|---|---|---|
| committer | Joerg Roedel <jroedel@suse.de> | 2019-02-26 11:07:05 +0100 |
| commit | e5567f5f67621877726f99be040af9fbedda37dc (patch) | |
| tree | adedf638da604e2a1340da262ee7d6faa4107983 /drivers/pci | |
| parent | 3f0c625c6ae714cf4dbab534b4c399f1d720e5db (diff) | |
| download | linux-e5567f5f67621877726f99be040af9fbedda37dc.tar.bz2 | |
PCI/ATS: Add pci_prg_resp_pasid_required() interface.
Return the PRG Response PASID Required bit in the Page Request
Status Register.
As per PCIe spec r4.0, sec 10.5.2.3, if this bit is Set, the device
expects a PASID TLP Prefix on PRG Response Messages when the
corresponding Page Requests had a PASID TLP Prefix. If Clear, the device
does not expect PASID TLP Prefixes on any PRG Response Message, and the
device behavior is undefined if the device receives a PRG Response Message
with a PASID TLP Prefix. Also the device behavior is undefined if this
bit is Set and the device receives a PRG Response Message with no PASID TLP
Prefix when the corresponding Page Requests had a PASID TLP Prefix.
This function will be used by drivers like IOMMU, if it is required to
check the status of the PRG Response PASID Required bit before enabling
the PASID support of the device.
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Keith Busch <keith.busch@intel.com>
Suggested-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Diffstat (limited to 'drivers/pci')
| -rw-r--r-- | drivers/pci/ats.c | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c index 5b78f3b1b918..420cd0a578d0 100644 --- a/drivers/pci/ats.c +++ b/drivers/pci/ats.c @@ -368,6 +368,36 @@ int pci_pasid_features(struct pci_dev *pdev) } EXPORT_SYMBOL_GPL(pci_pasid_features); +/** + * pci_prg_resp_pasid_required - Return PRG Response PASID Required bit + * status. + * @pdev: PCI device structure + * + * Returns 1 if PASID is required in PRG Response Message, 0 otherwise. + * + * Even though the PRG response PASID status is read from PRI Status + * Register, since this API will mainly be used by PASID users, this + * function is defined within #ifdef CONFIG_PCI_PASID instead of + * CONFIG_PCI_PRI. + */ +int pci_prg_resp_pasid_required(struct pci_dev *pdev) +{ + u16 status; + int pos; + + pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI); + if (!pos) + return 0; + + pci_read_config_word(pdev, pos + PCI_PRI_STATUS, &status); + + if (status & PCI_PRI_STATUS_PASID) + return 1; + + return 0; +} +EXPORT_SYMBOL_GPL(pci_prg_resp_pasid_required); + #define PASID_NUMBER_SHIFT 8 #define PASID_NUMBER_MASK (0x1f << PASID_NUMBER_SHIFT) /** |